Felbridge Flyers Turbo Jet PageFelbridge Flyers Radio Model Flying Club |
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"The engines are very quiet in the air, sounding like a super hair drier"
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Two of the members of Felbridge Flyers have
developed their own turbo jet or miniature gas turbine engines. For the
last four years Howard Denyer and Richard Green have been developing a
turbine engine base loosely on the ideas of Kurt Schreckling. It uses a
standard turbo-charger compressor linked to a specially produced turbine
wheel, initially machined from stainless steel but now precision cast in
Inconel.
They have encountered and overcome many difficulties during the manufacture. Seemingly very small differences to the design have major effects on the performance. Their first engine would hardly self sustain, let alone produce any thrust. The current HD4 engine produces about 14lbs of thrust at 105000 rpm and runs very reliably. The engines are started on propane gas using a small blower to get air moving through them. When the engine is running slowly on the gas liquid fuel is fed in and the gas turned off. A variable speed electric pump feeds the fuel (jet AA, paraffin or almost anything) and provides speed control. The engines are fitted with speed sensors to determine the revolutions and thermo-couples measure the exhaust temperature. Air from the compressor is used to pressurise the bearing oil supply tank to ensure the shaft bearings are lubricated. Fuel is stored in a hospital drip bag to ensure an uninterrupted supply, any bubbles could result in a flame out. The engines run at between 90000 to 105000 rpm but are very quiet in the air, sounding like a sort of super hair drier. Richard and Howard designed a flying wing "Ballistic" to test the engine. This has proved ideal and very controllable with small canard wings fitted ahead of the mainplane. They are also involved with projects at Sussex University using a turbine they have build in a large-scale "microlight" type airframe, also designed by them. The engine also powers a scale Hawker Hunter jet model which is looking very good. A Eurofighter Typhoon is the next model scheduled to have the engine which is being continually refined to improve performance and reliability. The engine plan, critical parts and control unit is available from Howard and Richard. Contact them for more detail on specification, price and availability by e-mail.
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